The present invention relates to a data processing apparatus and a data processing method with respect to data which includes video and/or audio data.
Recently, with the multiplication of channels for providing information in accordance with the spread of CATV (Cable Television), requests for new functions which can not be performed in a conventional VTR (Video Tape Recorder) are increasing, the new functions which can simultaneously record and reproduce a plurality of video/audio data in one video/audio data recording and reproducing apparatus or which can reproduce data while recording. To comply with these requests, an apparatus called video server (or AV (Audio and/or Video) server) for recording and reproducing images and/or sounds by using a random accessible recording medium such as a hard disk has been spreading.
Generally, a video server in a broadcasting station needs to have a large capacity of memory, in order to record a long term data in addition to a high transmission rate of necessary data due to requests of high picture quality and high sound quality. Then, a data recording and reproducing apparatus including a plurality of hard disks (hereinafter, referred to as HD) which can store video/audio data and can process in parallel is used to attempt to speed up a transmission rate and enlarge a capacity of memory, and to further attempt to secure the reliability by previously recording parity data if any of HD devices is out of order. Thereby, even if the channel numbers are different depending on the contents of programs tried to be provided by a broadcasting station and depending on the broadcasting form, material data comprising a plurality of audio/video data is recorded dispersedly to simultaneously output the data through multiple channels and to reproduce the same material data through the multiple channels with the reproduction time being shifted, so that a multichannel video server which can correspond to various usage forms such as the construction of systems of VOD (Video on Demand) or NVOD (Near Video on Demand) can be realized.
The data recording and reproducing apparatus used as the video server uses the RAID (Redundant Arrays Inexpensive Disks) techniques which is constructed by a plurality of hard disk drives (HDD) each comprising further a plurality of hard disks which has been described in a thesis (xe2x80x9cA Case for Redundant Arrays of Inexpective Disks (RAID)xe2x80x9d, ACM SIGMOND Conference, Chicago, Ill., Jun. 1-3, 1988) published by Patterson, 1988.
In the thesis described above, the RAID is classified into five, RAID-1 to RAID-5. The RAID-1 is a method of writing the same contents in two HDD. The RAID-3 is a method of dividing input data into a specific size to record it in a plurality of HDD, and forming parity data being exclusive OR of data block which corresponds to each HDD to write it in another single HDD. The RAID-5 is a method of enlarging a dividing unit (block) of data to record one divided data as data block in a single HDD, and recording the result of operating exclusive OR of data block which corresponds to each HDD (parity data) as a parity block in the other HDD and dispersing the parity block into the other HDD.
FIG. 9 shows the construction of the disk array apparatus described above.
The input data D1 is input to a disk array controller and is divided and dispersed into a predetermined unit (e.g., one byte unit or one bit unit) to be recorded in a plurality of hard disk drives (referred to as HDD) 2A to 2H. At the time of dispersion, the disk array controller calculates the parity data of the input data D1 and records it in a HDD 2H for parity data. At the time of reproduction, when the data dispersedly recorded in any of HDD 2A to 2G fails to be read, the parity data recorded in the HDD 2H for parity data is read to perform parity operation so as to perform an error correction. The data is thereby restored to be output.
However, at the time of recording or reproduction, when the data is not recorded or reproduced correctly due to a trouble of one of the HDD 2A to 2G and a trouble of one hard disk, a repeat processing (retry processing) is performed on the HDD 2A to 2G to repeatedly record or reproduce the data. Since the retry processing is repeatedly performed in this way, successively input data or data to be output can not be processed at a real time.
Specially, in case of using the disk array apparatus used in a broadcasting station as a recording and reproducing apparatus for recording and reproducing video and/or audio data or as a data outputting apparatus for outputting data actually used on a broadcasting, programs can not be broadcasted at a real time.
This invention is to solve the problems described above, and to provide a data outputting apparatus and the method thereby which can actually deal with a recording and reproduction processing at a real time.